1. Field of the Invention
The present invention relates to routers. More particularly, the present invention relates to an improved construction for mounting a router motor housing for repeatably precise and accurate concentric positioning relative to the base assembly at any vertical setting.
2. Description of the Related Art
There are basically two types of routers: fixed-base and plunge. A fixed-base router, also known as a standard router, has a base that clamps directly to a removable motor housing making the router one integral or "fixed" unit.
Virtually all fixed-base routers have mechanisms to clamp the motor in the router's base at a designated vertical position. To effect the desired depth of cut (the amount of the router bit projecting through the sub-base), the operator must move the router motor up and down and then clamp the motor to the base at the desired vertical position. In most router applications it is necessary to set the depth of cut accurately and precisely. Further, it is necessary in almost all router applications to maintain the bit as precisely as possible in a perpendicular relationship to the plane of the base and in a concentric relationship to the outside diameter of the base in all vertical positions of the motor.
Router base assemblies typically include an annular base member which rests on the workpiece. The annular base supports an upright, hollow cylinder in concentric relationship therewith. The hollow cylinder has a vertical slot and is associated with a clamping mechanism for opening the base cylinder to receive the cylindrical motor housing freely and for closing or squeezing the cylindrical base cylinder into tight engagement with the cylindrical motor housing. The inside diameter of the base cylinder, in its open or relaxed state, is necessarily greater than the outside diameter of the cylindrical motor housing. When the clamping mechanism is actuated to squeeze the base cylinder into tight frictional engagement with the cylindrical motor housing, the base cylinder will no longer maintain a true circular cross-section. In most cases, the clamped, now non-circular base assembly will engage the cylindrical motor housing at two diametrically opposed, vertical areas of contact. Thus, the motor housing is subject to being canted or cocked slightly with respect to the base cylinder in which event the router bit will not be in a precise perpendicular position with respect to the plane of the annular base member which rests on the workpiece. Accordingly, the resulting cutting operation may not be as precise as the operator expects or would like.